Cogent Biosciences Shares Fall Despite Positive Clinical Trial Updates For Systemic Mastocytosis Treatment

Cogent Biosciences Inc COGT shared data from Part 1 of its ongoing Phase 2 APEX trial evaluating bezuclastinib in patients with advanced systemic mastocytosis (AdvSM) at the American Society of Hematology Annual Meeting & Exposition.

As of the Sept. 25, 2023 data cutoff, bezuclastinib demonstrated a differentiated safety and tolerability profile across doses. 

Most adverse events were low-grade and reversible, and no related cognitive impairment or bleeding events were reported. Related serious adverse events were reported in four patients.

As of the data cutoff date of Sept. 25, 2023, 32 patients enrolled were evaluated for signs of clinical activity:

A 56% overall response rate (ORR) in TKI-naïve patients, included 86% ORR by pure pathological response (PPR) criteria and 100% ORR in APEX patients treated at 100 mg BID with exposures consistent with the go-forward dose.

A 150 mg QD optimized formulation dose selected for APEX Part 2 is expected to deliver patient exposures consistent with this cohort.

Nearly all patients demonstrated a significant improvement in biomarkers associated with disease burden.

A total of 79% achieved complete clearance of mast cell aggregates by central review

Cogent continues to actively enroll Part 2 of the APEX trial, which is expected to include approximately 65 AdvSM patients and is on track to complete enrollment by the end of 2024.

Cogent reported initial Part 1a data from SUMMIT Phase 2 trial of bezuclastinib in patients with nonadvanced systemic mastocytosis (NonAdvSM), showing rapid improvement in patient symptoms and improvement across all biomarkers with a safety and tolerability profile that supports the potential for chronic dosing. 

Cogent completed enrollment in SUMMIT Part 1 and plans to initiate SUMMIT Part 2 in 1H of 2024. 

In Gastrointestinal Stromal Tumors, Cogent is enrolling patients in Part 2 of the Phase 3 PEAK trial and remains on track to complete enrollment by the end of 2024.

Price Action: COGT shares are down 51.03% at $4.23 on the last check Monday.

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